The physical mechanism investigation of AC TDDB behavior in advanced gate stack

For the first time, the physical mechanisms for both AC TDDB improvement and degradation are investigated. For an optimized gate stack, the AC TDDB improvement is due to more charge de-trapping. For a non-optimized gate stack, the AC TDDB degradation can be explained through a proposed model which combines the charge redistribution and charge recovery. In addition, the fast measurement could provide a more reliable TDDB lifetime projection due to the minimization of the charge trapping and de-trapping effects during the TDDB stress.